1:1-ethylene-2:2-dipyridylium quaternary salts



United States Patent 3,2t32,5 lt Ifl-ETHYLENE-ZsZ-DIPYYLIUM QUATERNARY SALTS Ronald Frederick Homer, Wolringham, England, assignor to Imperial Chemical industries Limited, London, England, a corporation oi Great Britain No Drawing. Filed May 2, 1962, Ser. No. 191,749 Claims priority, application Great Britain, Aug. 25, 1561, 36,742/ 61 9 Claims. (Cl. 71-25) This is a continuation-in-part of application Serial No. 787,375, filed January 19, 1959, now abandoned.

This invention relates to new herbicides and more particularly it relates to dipyridylium quaternary salts which posses useful herbicidal properties.

The salts of the invention may be broadly described as l:I'-ethylene-2:2'-dipyridylium quaternary salts having a lower alkyl radical located at one or more positions selected from the 4, and 6 positions of the pyridylium ion and a lower alkyl radical located at one or more positions selected from the 4', 5 and 6' positions of the ion. These salts may be represented by the following formula:

GE -CH wherein the R and R substituents stand for lower alkyl, preferably alkyl containing from 1 to 4 carbon atoms, the R substituent being located at a position or positions selected from the group consisting of the 4, 5 and 6 positions and the R substituent being located at a position or positions selected from the group consisting of the 4', 5' and 6' positions and X stands for an anionic radical. Typically, R and R are methyl or ethyl and they are conveniently, but not necessarily the same.

Preferred compounds are the N:N'-etl1ylene-5:5-dimethyl-2:2'-dipyridylium salts, for example, the dibromide or dichloride, and the corresponding 4:4 and 6:6 derivatives.

It is to be understood that the expansion anionic radical includes such radicals derived from inorganic and organic acids and any such radical may be used herein. The said anionic radicals may be interchanged one with another without destroying the herbicidal activity of the products of this invention. As suitable anionic radicals derived from inorganic acids there may be mentioned, for example, halide radicals such as chloride, bromide, and iodide radicals while the p-toluene-sulphonate radical is representative of anionic radicals derived from organic acids. Other anionic radicals which may be mentioned are, or instance, sulphate, nitrate, bichrornate and thiocyanate.

According to a further feature of the invention there is provided a process for the manufacture of the said dipyridyl derivatives which comprises interaction of the corresponding dipyridyl compound of the formula:

wherein R and R have the meaning stated above and a quaternizing ethylene glycol di-ester.

As a suitable ethylene glycol di-ester there may be mentioned, for example, an ethylene d'dialide, for example, ethylene dibromide and an ethylene disulphonate, for example, ethylene di-p-toluenesulphonate.

The reaction may be carried out, for example, by heating the reagents together or they may be heated together in the presence of an inert solvent or diluent, preferably a ice high-boiling polar liquid, for example, nitrobenzene or ,B-ethoxyethanol.

The dipyridyl compounds used as starting material in the above process may be obtained according to the art, for example, by treatment of the appropriate 2-bromo-4- or S-alkylpyridine with copper powder.

Although the preparative process described above is quite satisfactory for the preparation of compounds where X is, for instance, a chloride, bromine, iodine or p-toluenesulphonate ion, the process is not always satisfactory for the preparation of other compounds of this invention. Accordingly, as another aspect of the invention, the compounds of this invention can be prepared by a second process, in which a quaternary salt of the formula given above is treated with a suitable salt of an acid having the anion of the quaternary salt it is desired to make. Stated another way, there is provided a process for the manufacture of certain of the new dipyridyl derivative which comprises interaction of a compound of the formula:

wherein R and R have the meaning stated above and Y stands for an anionic radical, for example, a bromide radical or a p-toluenesulphonate radical and obtainable by the previously described process, with a salt of an acid derived from an anionic radical X, wherein X has the meaning stated above.

Thus, those compounds of the formula given above wherein Y stands for halogen, for example, bromine can be converted into certain of the new quaternary salts of the invention by treatment with a salt, for example, sodium iodide or silver chloride. The said interaction may be carried out in the presence of an inert solvent or diluent medium, for example, water.

As particularly useful quaternary salts, there may be mentioned, for example, those salts of the formula stated above wherein X stands for a bromide, chloride, iodide or p-toluenesulphonate radical.

The said new quaternary salts possess useful herbicidal properties. For example, these salts are useful as general herbicides against such representative plant species as wheat (Triticum aestz'vum), wild oats (Avemz fatua), sugar beet (Beta vulgaris), mustard (Sinapis alba), kale (Brassica oleracea), cleavers (Galium aparine), and red clover (T rifolium pratcnse). Thus, according to a further feature of the invention, there are provided herbicidal compositions wherein the active herbicidal ingredient comprises one or more of the said new quaternary salts. Such compositions may be liquid compositions and may be, for example, aqueous solutions of the said new quaternary salts.

The said liquid compositions may advantageously contain auxiliary agents, for example, dispersing agents or wetting agents. The wetting or dispersing agent used can be a cationic or non-ionic surface-active compound, but in general anionic compounds should be avoided as these are likely to interact with the dipyridylium quaternary salt and lead to undesirable side effects. Suitable wetting agents may be, for example, condensation products of ethylene oxide with, for example, an alkyl phenol, for example, octylcresol such that the said condensation products contain about one molecular proportion of octyloresol condensed with about 8-10 molecular proportions of ethylene oxide.

The said liquid compositions may also contain additional ingredients, for example, agents which improve the adhering properties of the said liquid compositions to the plant, for example, sodium carboxymethylcellulose and ammonium polymethacrylate.

The herbicidal compositions may. also conveniently be in the form of solid compositions in which, the new quaternary salts are admixed with inert pulverulent diluents, for example, talc, china clay, gypsum, basic slag, kieselguhr or bentonite and other colloidal clays. These pow-.

der compositions can also contain a wetting or dispersing agent if desired.

Whilethe quaternary salts of the invention may be used for general herbicidal purposes as aforesaid, they are particularly useful as selective herbicides against grass species. 7 This selective activity is unexpected and represents a very significant and advantageous distinction over the corresponding unsubsituted quaternary salts, i.e. the salts where R and R stand for hydrogen (U.S. Patent 2,823,987).

' The invention is illustrated but not limited, by the following examples in which the parts are by weight:

v EXAMPLE 1 i A mixture of 4 parts of :5'-dimethyl-2:2-dipyridyl,

parts of ethylene dibromide and 25 parts of nitrobenzene is heated at 170180 C., for 8 hours and then cooled.

. The mixture is filtered and the solid residue is dissolved in V parts of hot water, treated with carbon and filtered.

The filtrate is then diluted with '100 parts of acetone and the mixture is filtered. The solid residue so obtained is N:N-ethylene-5:5'-dimethyl 2:2 dipyridylium dibromide, M.P. 330-335 C., with decomposition.

EXAMPLE 2 V A mixture of 16- parts of 4:4'-dimethyl-2:2'-dipyridyl,l

' dipyridylium dibromide, M.P. 268-270 C.

The N:N'-ethylene4,5 z4',5-tetramethyl-2:2-dipyridyl ium dibromide or the corresponding 4,6:4',6-te tramethyl or 4,5,6:4',5',6'-hexamethyl-derivatives may be prepared in essentially the same manner starting with 4,5:4',5-tet-ramethyl-2 2-dipyridyl, 4,6 :4,6-tetramethyl-2 2'-dipyridyl and 4,5,6:4,5', 6-hexan1ethyl2':2'-dipy ridyl, respectively.

EXAMPLE 3 A mixture of 6.5 parts of 4:4-diethyl-'2:Zf-dipyridyl and 40 parts of ethylene dibromide isheated under reflux at 140 C. for 16 hours and cooled. The mixture is filtered and the solid residue is dissolved in 50 parts of ethanol, treated with carbon and filtered. The filtrate is evaporated to dryness and the residue is triturated with acetone and filtered. The solid residue so obtained is NzN ethylene-4:4-diethyl-2:2-dipyridylium dibromide, M.P. 310 C. 1 V V EXAMPLE 4 V A mixture of 9.2 parts of 5:5'-dimethyl-2:2-dipyridyl, parts of ethylene di-p-toluenesulphonate and 60 parts of nitrobenzene is heated at 160170 C., for 3 hours and then cooled. The reaction mixture is added .to 300 parts of acetone and the mixture is filtered. The solid residue is dissolved in aqueous ethanol, treated with carbon and filtered. The filtrate is diluted with acetone and the mixture is filtered; The solid residue so obtained is.NtN'- ethylene 525, dirnethyl-2z2' dipyridyl di-p-toluenesulphonate, M.P. 220 C.

EXAMPLE 5 and the resulting aqueous solution boiled with charcoal and filtered. The filtrate obtained was evaporated to dryness leaving a residue which was then recrystallized from a mixture of methanol and acetone, and the quaternary salt N:N-ethylene 6:6'-dimethyl'- 2:2 dipyridylium dibromide was thus isolated as a white crystalline solid, melting point about 320 C., with darkening and shrinking.

EXAMPLE 6 A mixture of one part or" 6:6-dimethyl-2:2'-dipyridyl, 10.9 parts of ethylene dibromide and 18 parts of nitrobenzene was heated underreflux for 8 hours. The resulting mixture was cooled, mixed with 80 parts of ether, and the'precipitate thus obtained was collected. This precipitate was then dissolved in water and N:N'-ethylene-6:6'- dimethyl-Z:2-dipyridylium dibromide was isolated from the resulting aqueous solution by the method used for treating the aqueous solution referred to' in Example 5.

. EXAMPLE 7 V A solution of 1 partof N:N'-ethylene-5:ST-dimethyl- 2:2'-dipyridylium dibromide in 800 parts of water containing 2.4 parts of a condensation product oi octylcresol with 8-10 molecular proportions of ethylene oxide (as ing representative plant species: wheat (Triticum aestia 7 amount of 20 gallons/ acre.

pyridylium salt applied to the plant species by using the .four aqueouscompositions corresponded to rates of 4, 2, 1

A mixture of one part 6:6-dimethyl-2:2'-dipyridyl and cooled, its contents dissolved in a small quantity of water.

wetting'agent) is sprayed at the rate of 20 gallons to the acre on to a mixed stand of seedling plants.

sugar beet (Beta. vulgaris) and red clover (T rifolium repens), and severe damage to wheat (Triticum aestivum) kale (Brassica oleracea moe'llerii) and mustard (Sinapis alba).

EXAMPLE 8' A solution of 5 parts of N:N-ethylene-4:4'-dimethyl- 2:2'-dipyridylium dibromide in 1000 parts of water containing 3 parts of a condensation product of octylcresol with 8-10 molecular proportions of ethylene oxide (as wetting agent) 'is sprayedat the rate of gallons to the After 14 and mustard (Brassica alba) I ,7 7 EXAMPLE 9 An aqueous solution of N:N'-ethylene-6:6'-dimethyl- 2:2'-dipyridylium' dibromide was sprayed on the followvum) wild oats (Avena fat ua mustard (Sinapis albw),

kale, (Brassica oleracea), sugar beet (Beta vulgaris), red 7 clover (Trifolium pratense) and cleavers (Galium aparine). Fouraqueous compositions were tested, containing respectively 0.2, 0.1, 0.05, 0.025 lb./ gallon of the test. chemical, each composition containing 0.1% by 'weight of a wetting agent consisting of a condensation product of one mole of p-octyl phenol with 78 moles of ethylene oxide. The four aqueous compositions were sprayed on the. seven representative plant species in an Thus, the amount of the diand 0.5 lb. of test chemicalZ acre. p

The results obtained seven days after spraying are set out'in the table below in which the herbicidal activity of each of the compositions tested is indicated by a grading number from 0 to 4. V

. These grading numbershave the following meanings:

0Complete kill 1Very severe damage with partial kill 2Severe damage 3-Moderate damage 4-S1ight damage It will be seen that at the rate of 2 lb./ acre 'a complete kill was obtained of all the plant species tested with the After 14' days there is complete kill of wild oat (Avena fatua),

exception of wheat which was, however, very severely damaged.

Rate 0fapplica- Wheat Wild Sugar Mustard Kale Cleavers Clover tion (lbJacre) oats beet D 0 0 Cl 0 0 0 l 0 O 0 0 0 0 l 0 1 0 0 3 0 l 0 D 1 O i 1 EXAMPLE the grass species. In fact, the ratio of the 5:5'-dimethyl This example illustrates the unique selectivity of the compounds of the present invention against grass species and for this purpose, a preferred dipyridylium salt of 2,823,987, N:N'-ethylene 2:2 dipyridylium dibromide, was subjected to the following comparative tests with the dimethyl-substituted analogs of Examples 1, 2 and 5 herein.

The four compounds were each applied to a standard range of test plant species by spraying the plants with aqueous solutions of a concentration corresponding to /s lb. :in 100 imperial gallons 'of water per acre, the solutions each containing 1% by weight of a non-ionic Wetting agent containing a condensate of p-nonyl phenol and ethylene oxide.

The sprayed plants were examined during the following 9 days and the damage suffered by the plants on the ninth day was assessed as a percentage compared with healthy (100%) replicate plants which had not been sprayed. The results obtained are shown below in Tables 1 and 2 which relate respectively to broad-leaved species and grass species. The figures for broad leaved species were obtained as mean values for the species mustard, kale, sugar beet, cleavers and clover, and the figures for grasses as mean values obtained for Wheat and wild oats.

Table 1 PERCENTAGE DAMAGE TO BROAD-LEAVED SPECIES AT 9 DAYS Compound: Percentage N:N'-ethylene-2:2-dipyridylium dibromide 60 4:4'-dimethyl analogue (Example 2) 16 5:5-dimethyl analogue (Example 1) l6 6:6'-dimethyl analogue (Example 5) 36 Table 2 PERCENTAGE DAMAGE TO GRASS SPECIES AT 9 DAYS Compound: Percentage N:N-ethylene2:2'-dipyridylium dibromide 50 4:4'-d imethyl analogue (Example 2) 30 5:5-dimethyl analogue (Example 1) 60 6:6-dimethyl analogue (Example 5) 60 From the data in the above tables, an index of selectivity, representing the ratio of percentage damage on grass species to damage on broad leaved species at 9 days, was calculated for each compound. A value of 1.0 for this represents no selectivity while index value above 1.0 shows a selective activity against the grass species. The index values for the four compounds tested at 9 days are shown below in Table 3.

Table 3 Compound: Index of selectivity N:N-ethylene-2:2'-dipyridylium dibromide 0.83 4:4-dimethyl analogue (Example 2) 1.89 5:5-dimethyl analogue (Example 1) 3.70 6:6'-dimethyl analogue (Example 5) 1.67

derivative is almost 4 and, in each instance, the index for the dimethyl analogue is at least twice the index for the N:N-ethylene-2:2-dipyridylium dibromide. This is illustrative of the unexpected and unique characteristics of the products of the present invention. These products also function more slowly than the non-alkylated counterparts and are, therefore, more advantageous in those cases where a slower rate of activity is claimed. The unusual nature of the present products is further evident from the fact that the 3:3'-dialkyl isomers demonstrate little or no herbicidal activity when compared to the 4:4'-, 5:5'- and 6:6-derivatives described herein.

What is claimed is:

l. A 1:l'-ethylene-2:2-dipyridylium quaternary salt having a lower alkyl radical substituent located at a position selected from the 4, 5 and 6 positions of the dipyridylium ion and a second lower alkyl radical located at a position selected from the 4', 5 and 6' positions of the said ion.

2. N:N-ethylene-5:5'-dimethyl-2:2-dipyridyliiun dichloride.

3. N:N'-ethylene-4:4'-din1ethyl-2:2'-dipyridylium dichloride.

4. N N'-ethylene-6 6'-dirnethyl-2 2'-dipyriclylium dichloride.

S. A herbicidal composition comprising, as the active herbicidal ingredient, a herbicidally effective amount of a 1:l-ethylene-2:2'-dipyridylium quaternary salt having a lower alkyl radical substituent located at a position selected from the 4, 5 and 6 positions of the dipyridylium ion and a second lower alkyl radical located at a position selected from the 4', 5' and 6' positions of the said ion, a herbicide carrier and a surface-active agent.

6. The method of selectively controlling grass species which comprises applying thereto a herbicidally effective amount of a 1:l'-ethylene-2:2'-dipyridylium quaternary salt having a lower alkyl radical substituent located at a position selected from the 4, 5 and 6 positions of the dipyridylium ion and a second lower alkyl radical located at a position selected from the 4, 5' and 6' positions of the said ion.

7. The quaternary salt of claim 1 wherein the alkyl radicals are methyl radicals in the 5 and 5' positions.

8. The quaternary salt of claim 1 wherein the alkyl radicals are methyl radicals in the 4 and 4 positions.

9. The quaternary salt of claim 1 wherein the alkyl radicals are methyl radicals in the 6 and 6' positions.

References Cited by the Examiner UNITED STATES PATENTS 2,823,987 2/58 Fielden et al. 260-268 NICHOLAS S. RIZZO, Primary Examiner, 

1. A 1:1''-ETHYLENE-2:2''DIPYRIDYLIUM QUATERNARY SALT HAVING A LOWER ALKYL RADICAL SUBSTITUENT LOCATED AT A POSITION SELECTED FROM THE 4,5 AND 6 POSITIONS OF THE DIPYRIDYLIUM ION AND A SECON LOWER ALKYL RADICAL LOCATED AT A POSITION SELECTED FROM THE 4'', 5'' AND 6'' POSITIONS OF THE SAID ION.
 6. THE METHOD OF SELECTIVELY CONTROLLING GRASS SPECIES WHICH COMPRISES APPLYING THERETO A HERBICIDALLY EFFECTIVE AMOUNT OF A 1:1''-EHTYLENE-2:2''-DIPYRIDYLIUM QUATERNARY SALT HAVING A LOWER ALKYL RADICAL SUBSTITUENT LOCATED AT A POSITION SELECTED FROM THE 4,5 AND 6 POSITIONS OF THE DIPYRIDYLIUM ION AND A SECOND LOWER ALKYL RADICAL LOCATED AT A POSITION SELECTED FROM THE 4'',5'' AND 6'' POSITIONS OF THE SAID ION. 